Circuit for controlling alternating currents



April 27, 1965 J. H. KUYKENDALL CIRCUIT FOR CONTROLLING ALTERNATING CURRENTS I Filed March 24, 1961 T 1 -1 INVENTOR (DME'S Au Y/(ENDALL BY %MM/ ,L V ATTORNEYS amount of heat furnished by the resistors.

United States Patent "ice Thisinvention relates to a circuit for supplying a plurality of load impedances with variable currents for changing the electrical power delivered to the load combination. The invention has particular reference to a switching control system for supplying two lamps or two heater resistors with variable currents for varying the amount of light delivered from the lamps or the The invention is not restricted to lamps and heaters but may be used in connection with any plurality of electrical load devices. 7 v

Switching arrangements for the electric heaters used in stoves have been complicated by the fact that it has been necessary to connect a three-wire supply line to the source of electrical power in order to produce all the heatin. variations generally considered necessary for a stove. Also, the electrical switching means necessary for producing variations of light from a single bulb have included two unequal filaments within the bulb and even then only three variations of illumination have been possible. It is well-known that a variable voltage transformer can be used in connection with both heaters and lamps but these transformers are bulky and expensive.

One form of the present invention uses two unequal loads and by the use of two diode rectifiers produces six variations of light or heat. These variations are produced without the aid of additional resistors, transformers, or inductors and the control means does not generate any appreciable amount of heat.

One of the objects of this invention is to provide an improved circuit for the control of alternating currents which avoids one or more of the disadvantages and limitations of prior art arrangements.

Another object of the invention is to control the amplitude of alternating currents through a system of loads without the use of transformers, inductors, or power absorbing resistors.

Another object of the invention is to reduce the power of current control systems.

Another object of the invention is to reduce the heat generated in current controlled systems.

Another object of the invention is to eliminate the usual inductive spark which is normally present when switching means are used in connection with inductors or transformers.

The invention comprises a current control system for a plurality of loads supplied with alternating current power and includes a pair of terminals, for connection to a power source. Switching connections are arranged between the terminals and the load for applying varying voltages to the loads. The switching connections include a combination of switching means and a plurality of diode rectifiers arranged for sequentially connecting the loads across the terminals, singly and in combination.

The switching means also connects the loads in series with 3,180,999 Patented Apr. 27, 1965 FIG. 1 is a schematic diagram of connections showing two lamps of unequal wattage connected through two dial switches in connection with two diode rectifiers.

FIG. 2 is a schematic diagram of connections similar to FIG. 1 but showing the switching means combined by the use of single arm and controlling two heating resistors of unequal value.

Referring now to FIG. 1 the circuit includes two terminals 1t and 11 which are connected through two dial switches 12 and 13 to two lamps 14 and 15. The lamps may have any value but usually are selected so that one lamp 15, uses twice as much power as the other lamp 14. The switching means 12 and 13 are connected to diode rectifier 16 and 17 respectively and, in addition, each switching means has seven contact points 18 which are sequentially connected to switch arms 20 and 21 to vary the power to the lamps.

The diode rectifiers 16 and 17 may be any type of rectifier component but it is contemplated that silicon rectifi-ers will be used in this circuit because they are capable of handling high currents and are not adversely influenced by elevated temperatures up to and including degrees C.

The contact arms 2 and 21 are mechanically joined so that they may be turned in unison by a single control knob. The two contact arms are electrically connected together and to one of the supply terminals 14). The two lamps 14 and 15 have one of their terminals connected to the other supply terminal 11. The other connections from the lamps to the diodes and the contact points will be pointed out when the operation is described.

With the switch arms shown in FIGURE 1 turned all the Way to the left, there is no connection between the input terminal 11 and the two lamps and this is the off position. With the arms 20 and 21 turned to the next contact point, current from terminal 18 flows through both lamps 14 and 15 to the other terminal 11, thereby providing both with maximum current and producing the greatest amount of illumination. When the contact arms are turned to the third contact point the full voltage is still applied to lamp 15, producing its normal maximum illumination, but the current through lamp 14 now is connected in series with rectifier unit 17 and thereby receives only one-half of the wave. Rectifier 17 may be inserted in the circuit in either direction to provide either the positive or the negative halves of the alternating current. 1

When the contact arms 26 and 21 are turned to the fourth contact point no current passes through the smaller lamp 14 but the full current is applied to the larger lamp 15. When the contact arms are turned to the fifth position, current is applied to both lamps through rectifiers. In order to partially equalize the load on the supply system, one of the rectifiers 16 may supply lamp 15 with the negative halves of the wave while rectifier 17 may be connected so as to supply the positive halves of the wave to lamp 14. However, this arrangement is not necessary and the rectifiers 16 and 17 may be connected in any manner desired. When the switch arms are connec-ted to the sixth position, no current flows through the smaller lamp but current is applied to the larger lamp '15 in series with rectifier 16, thereby providing a still lower. amount of illumination. When the contact arms are turned to the seventh and last position 'no current flows through the larger lamp but current is applied to the smaller lamp 14 in series with rectifier diode 17 to provide the smallest amount of illumination available.

Referring now to FIG. 2, a similar circuit is shown having supply terminals 11) and 11 and a single dial switch 22 having a single arm 23 which extends on both sides of a central shaft 24 and makes contact with two points, one at each end. The loads in this figure are shown as heating resistors of 1,000 watts and 500 Watts, each. As in FIG. 1, one side of each of these heating elements is connected to terminal lll while the other sides are connected to contact points on the dial switch 22 Rectifiers l6- and 17 are connected in the circuit in the same manner as shown in the first figure. With the switch arm turned to make contact with terminals A, no current flows through the heaters and the switch is in the off position. .Now, as the switch arm is turned in a clockwise direction to make contact with the other contact points in succession, the amount of power applied to the resistors is reduced from a maximum value to a minimum value as indicated by the figures adjacent to the contact points. The total wattage starts at 1,500 watts and is successively reduced to 1,250, 1,000, 750, 500 and 250.

It will be obvious from the foregoing description that three or more lamps or resistors can be combined to produce a wide variety of illumination or heating values. It will also be obvious that other loads besides lamps and heating resistors may be employed.

The foregoing disclosure and drawings are merely illustrative of the principles of this invention and are not to be interpreted in a limiting sense. The only limitations are to be determined from the scope of the appended claims.

I claim: I

1. A current control circuit for two loads comprising: a pair of input terminals for connection to a source of alternating current power; a first and second'load each having one of its ends connected to one of said pair of input terminals; a first and second rectifier, the first rectifier having its cathode connected to the first of the loads, the second rectifier having its anode connected to the second load; and a multiple switching means including two rotatable arms connected together and t0 the other input terminal; said arms each adapted to make contact with a plurality of stator terminals and thereby sequentially connect:

(1) the two loads in parallel across the input terminals,

(2) the second load to the terminals and the first load to the terminals in series with the first. rectifier,

(3) the second load to the terminals,

(4) the second load to the terminals in series with the second rectifier and the first load to the terminals in series with the first rectifier,

(5) the second load to the terminals in series with the second rectifier, and

(6) the first load to the terminals in series with the first rectifier.

2. A current control circuit as claimed in claim 1 wherein said loads are unequal and thereby dissipate unequal amounts of electrical power.

3. A current control circuit as claimed in claim 1 UNITED STATES PATENTS 1, 09,072

5/33 Prescott 307-57 2,303,460 12/42 Hodgkins a 219-20.1 2,896,125 7/59 Morton 323- 9 3,061,744 10/62 Spira g 307-146 LLOYD McCOLLUM, Primary Examiner.

. MILTON O. HIRSI-IFIELD, Examiner.

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1. A CURRENT CONTROL CIRCUIT FOR TWO LOADS COMPRISING: A PAIR OF INPUT TERMINALS FOR CONNECTION TO A SOURCE OF ALTERNATING CURRENT POWER; A FIRST AND SECOND LOAD EACH HAVING ONE OF ITS ENDS CONNECTED TO ONE OF SAID PAIR OF INPUT TERMINALS; A FIRST AND SECOND RECTIFIER, THE FIRST RECTIFIER HAVING ITS CATHODE CONNECTED TO THE FIRST OF THE LOADS, THE SECOND RECTIFIER HAVING ITS ANODE CONNECTED TO THE SECOND LOAD; AND A MULITPLE SWITCHING MEANS INCLUDING TWO ROTATABLE ARMS CONNECTED TOGETHER AND TO THE OTHER INPUT TERMINAL; SAID ARMS EACH ADAPTED TO MAKE CONTACT WITH A PLURALITY OF STATOR TERMINALS AND THEREBY SEQUENTIALLY CONNECT: (1) THE TWO LOADS IN PARALLEL ACROSS THE INPUT TERMINALS, (2) THE SECOND LOAD TO THE TERMINALS AND THE FIRST LOAD TO THE TERMINALS IN SERIES WITH THE FIRST RECTIFIER, (3) THE SECOND LOAD TO THE TERMINALS, (4) THE SECOND LOAD TO THE TERMINALS IN SERIES WITH THE SECOND RECTIFIER AND THE FIRST LOAD TO THE TERMINALS IN SERIES WITH THE FIRST RECTIFIER, (5) THE SECOND LOAD TO THE TERMINALS IN SERIES WITH THE SECOND RECTIFIER, AND (6) THE FIRST LOAD TO THE TERMINALS IN SERIES WITH THE FIRST RECTIFIER. 